I just switched to kubuntu feisty and immediately set up ktorrent. I opened the necessary ports on my modem, iptables and firestarter, however, I'm only downloading at 30-40 KBs. Before I switched, I was downloading the same torrent from the same site using utorrent on xp and my speed was 80-100 KBs. I also tried several torrents which I previously downloaded on utorrent and xp .. seeders and leechers in the thousands .. and the most I got was 40KB when I was once hitting 150 KBs. I'm using the same settings on ktorrent that I used on utorrent and I didn't switch providers.
What could be wrong?

Version ?

The likelihood is that you simply don't have everything set up as before.

Check to see if you're seeing the same number of peers, both seeds and leeches. Check to see that you have the proper ports open. Check to see that KTorrent isn't using too much upload bandwidth, and choking you.

I not only see quicker connections (i.e. peers start lining up immediately that I start KTorrent) but data flows in/out almost immedaitely that the app runs. You're experiencing the opposite!

Are you using the peerfilter? Did you use Peerguardian or other with uTorrent?

...ver 2.1 .. which is weird, because I asked the package manager to update it. Guess I'm going to have to update it manually.

I changed the tcp port and torrents that normally have lots of peers get high KB rates. So, it's mostly fine now.

Before I punched the required holes in iptables, I saw a message in Firestarter's events tab that said udp port 4445, the DHT port, was being blocked. After I punched a hole in iptables, I no longer saw that message, but I don't see any activity on it in Firestarter's Active Connections window. Is that important in any way?

I think it's the torrents that rely on DHT that are slow.

Have you tried 2.2 yet ?